This invention concerns a cooling chamber for rolled products.
The cooling chamber according to the invention is installed in rolling lines downstream of the last finishing stand so as to quench the rolled product and/or between the single finishing stands to cool the rolled product passing through and to keep it at the desired temperature.
The cooling chamber according to the invention enables the rolled product passing through to undergo a thermal treatment so as to provide the required physical and mechanical properties.
The cooling chamber according to the invention is employed advantageously, but not only, to cool round reinforcing bars used in reinforced concrete.
The state of the art of rolling lines has included for a long time now the method of cooling rolled products downstream of the last finishing stand and/or between the finishing stands so as to obtain rolled products having the desired physical and mechanical properties.
In that method it is very important that the rolled product should pass through the cooling means without obstructions and should undergo an even and intense cooling action along its whole length.
So as to achieve this result, cooling chambers have been used which contain an axial through bore, within which the rolled product runs axially and cooperates with a cooling fluid under pressure, which is generally water delivered into the cooling chamber.
The cooling fluid in the cooling chambers of the state of the art can run in the same direction as and/or in the opposite direction to the rolled product so as to achieve the most intimate contact with the rolled product in order to cool the latter as quickly and evenly as possible.
Various embodiments have been disclosed for improving the heat exchange between the cooling fluid and the rolled product.
One embodiment arranges to deliver the cooling fluid into the cooling chamber through a plurality of radial holes located at regular intervals in the circumference of the chamber.
In another form of embodiment the cooling chamber includes a casing closed upstream by an axially bored slider and downstream by a flange containing an axial tapered bore coaxial with the slider.
The head of the slider has a truncated-cone conformation which cooperates with the tapered bore of the flange to define an annular hole for the passage of the cooling fluid, which enters the casing through a radial hole in the casing.
The width of the annular hole can be varied by positioning the slider longitudinally.
The results attained by using these embodiments have enabled rolled products to be produced with the desired properties.
The problem entailed by these cooling chambers of the state of the art is linked to the fact that, so as to achieve the required cooling of the rolled product, it is necessary to use a great quantity of cooling fluid, thereby involving high costs for the supply of the cooling fluid and for the conveying and treatment of the fluid before it is discharged.
Another problem of the cooling chambers of the state of the art arises from the corrosion which the threaded coupling portions connecting the slider to the casing undergo owing to the continuous and prolonged contact with water (see for instance EP-A-0141511 and FR-A-1584095).
Another drawback of the cooling chambers of the state of the art arises from the fact that, where a plurality of cooling chambers are arranged in series one next to another, the water leaving the upstream element and heated by contact with the rolled stock to be cooled tends to enter the downstream element, thus impairing the efficiency of the cooling and creating problems which sometimes cannot be overcome at the intake of the rolled stock.
Another drawback of the cooling chambers of the state of the art arises from the geometric shape of the downstream segment of the slider within the cooling chamber, for this shape provides either a segment at an angle to the axis of the chamber (EP-A-0312843, FR-A-1584095--FIG. 3, DE-U-7134676) or a segment parallel to that axis (FR-A-1584095--FIG. 5).
The conformation of this downstream segment of the slider determines the development of the flow within the cooling chamber and thus conditions the efficiency of the cooling action.
These conformations of the state of the art are not the most advisable and suitable for maximising the cooling action performed by the cooling liquid on the rolled stock passing through.